The present invention relates to an oscillographic device for displaying multiple input signals and particularly to such a device for avoiding apparent breaks in waveform presentation.
Multiple traces depicting multiple inputs may be displayed with a single beam oscilloscope by time sharing the oscilloscope's electron beam between different inputs. The sampling rate or switching rate between the different inputs is normally faster than the horizontal sweep rate of the oscilloscope such that only segments of the individual input signals are actually presented during a given sweep. However, the sweep rate is usually sufficiently high, and the switching rate and sweep rate sufficiently asynchronous, that gaps are not actually observed in the presentation but are "filled in" on successive traces.
Visible breaks in the display of multiple signals are more likely to appear to the viewer when the oscilloscope sweep period (normally a multiple of the input signal period) is also a near multiple of the display switching period. Thus, if the switching between input signals becomes "synchronized" with the oscilloscope's sweep period, then the breaks in the waveforms appear near the same location on each successive trace and are viewed in the same manner as an input signal would be viewed. The visible breaks are most likely to occur when crystal controlled signals are observed on an oscilloscope with crystal controlled display switching.